Direct conversion chemical processing arc heater



y &1970 D. A. MANIERO ET AL 3,522,015

DIRECT CONVERSION CHEMICAL PROCESSING ARC HEATER Filed Feb. 16, 1966 2Sheets-Sheet 1 M258 N2 @E om mm A INVENTORS Dunlel A.M0niero 0nd l Ch%;(s 8. Wolf mm mm 5 mm mm mm ATTORNEY July 28, 1970 D, MANIERO ET AL3,522,015

DIRECT CONVERSION CHEMICAL PROCESSING ARC HEATER Filed Feb. 16, 1966 2Sheets-Sheet 2 mioww Q21 od} vw mm om w. o w w o o NINQ w wm w \ul 9 ONon ow om United States Patent US. Cl. 23277 Claims ABSTRACT OF THEDISCLOSURE An arc heater has a pair of axially spaced annular electrodesforming a gap with a generally axially extending arc therebetween, theelectrodes having magnetic field coils therein for generating a magneticfield which exerts a force on the arc and cause it to move substantiallycontinuously around and between the electrodes and to describe agenerally annular or cylindrical path. Process gas to be pyrolized issubstantially continuously admitted under pressure into the arc heaterthrough a substantially circumferential admission path radially externalto the electrodes from which it passes rapidly in a generally radialdirection through the gap between electrodes and through the annularpath described by are movement and into an arc chamber. The arcdescribes its annular path at such a fast repetitive rate that pyrolysiswith substantially uniform heating of the process gas are obtained. Thearc chamber is elongated providing a long path for process gas betweenarc pyrolysis area and exhaust area; cooling of the pyrolized gas to atemperature at which a a desired recombination product is present insubstantial proportion may occur within the arc chamber. Quenching gasmay be introduced into the arc chamber at one or more axially spacedpositions along the path of the process gas. The volumetric capacity ofthe arc chamber is increased by having the upstream end of the arcchamber closed in a substantial axial distance from the upstreamelectrode.

This invention relates to improvements in arc heaters, and moreparticularly to an improved arc heater for the processing of one gas andthe conversion thereof to another desired product gas, or carbon.

It has been known for some years that an electric arc may be used topyrolyze a gas, and after the gas has been decomposed into atoms andfree radicals, the atoms and free radicals may recombine to produce adifferent and desired product gas, depending upon the temperature towhich the decomposed gas is quenched or cooled and the speed with whichit is cooled after pyrolysis takes place. Sometimes an auxiliary gas maybe added to assist in rapid cooling.

The arc heater of our invention utilizes an arcto pyrolyze the processgas or feed stock, for example OH; or C H which is thereafter quenchedand cooled, so that a substantial yield of the product gas, for exampleC H is obtained. The arc heater of our invention is especially suitablefor handling high flow rates of the process gas, and for producing theproduct gas with a minimum of kilowatt hours of electricity to the arcper pound of the product gas. For example, in one experimental test runof our arc heater, methane (CH was utilized as a process gas with a flowrate of 0.275 lbs. per second. The power to the arc electrodes was 840kilowatts, and the acetylene, C H yield was 5.03 kilowatt hours ofelectricity utilized by the arc, per pound of acetylene C H a figurewhich compares very favorably with other processes now in general use,such as the Du Pont process and Huels process.

Accordingly a primary object of our invention is to 3,522,015 PatentedJuly 28, 1970 MIC provide a new and improved direct conversion chemicalprocessing arc heater.

Another object is to provide a new and improved chemical processing areheater in which large flow rates of a process gas may be employed.

Still a further object is to provide a new and improved arc heater forchemical processing in which the kilowatt hours per pound of a productgas are maintained at a low value.

These and other objects will become more clearly apparent after a studyof the specification, when read in connection with the accompanyingdrawings, in which:

FIG. 1 is a cross-section through the direct conversion chemicalprocessing are heater according to the preferred embodiment of ourinvention; and

FIG. 2 is a graph illustrating the operation of the apparatus of FIG. 1.

Referring now to the drawing of FIG. 1 for a more detailed understandingof the invention, a pair of fluid cooled electrodes 11 and 12 have anare 13 therebetween. It is seen that the electrodes 11 and 12 areannular in shape, and that each of the electrodes has an annularmagnetic field producing coil therein, these being designated 14 and 15respectively. If desired, field coils 14 and 15 are energized by directcurrent, the leads to the coil 14 being shown at 16 and 17 passingthrough a passageway 18, the leads to coil 15 being shown at 21 and 22passing through passageway 23. Coils 14 and 15 may be energized bydirect current with their fields in opposition so that a magnetic fieldis produced between electrodes which is substantially transverse to thepath of the are 13 and which exerts a force on the are 13 which causesit to rotate substantially continuously around the annular arcingsurface of the electrodes in a conventional manner. The rotation of anare by a magnetic field has been described elsewhere in the literatureof the art and in prior art patents and need not be described in detail.

Coil 14 is seen to be mounted in an annular housing 24 composed ofinsulating material, the housing 24 being disposed within an annularcup-shaped member 25 which is generally U-shaped in cross section, whichhas ends 26 and 27 thereof abutting against annular shoulders 28 and 29of an electrode supporting and fluid channeling member 30. Thecup-shaped member 25 is seen to be spaced from the inner wall of thegenerally U-shaped electrode 11 providing fluid passageways 31, 32 and33. It is seen that the portion of the fluid passageway 31 at thelefthand end thereof communicates with a fluid header 34, which may be afluid inlet header, and which has fluid inlet 35. Passageway 33 aroundthe other side of the coil and coil housing communicates by way of aplurality of circumferentially spaced passageways 36 and 37 with a fluidheader 38 which may be a fluid outlet header. In actual practice in theconstruction of the arc heater of the figure, two fluid inlets spacedapart are provided for the fluid inlet header 34, there being an inletin addition to the inlet shown at 35; and in addition there are twofluid outlets 39, only one being shown for simplicity of illustrationfor the fluid outlet header 38, the fluid outlets being preferablyspaced 180 apart.

The internal construction of the other electrode 12 is similar to thatof the electrode 11 and need not be described in detail. Fluidpassageways 41, 42, and 43 around the three sides of the field coil 15communicate, one with fluid outlet header 44 and another with fluidinlet header 45. Fluid inlet header 45 is seen having the inletpassageway 46 communicating therewith, and outlet header 44 has outlet47.

Between the two electrodes 11 and 12 there is a heat shield enclosingthe chamber in which the arc takes place, this heat shield including twogenerally annular ring members 51 and 52, separated by a center ring 53.The

two annular L-shaped ring members generally designated 51 and 52 eachhas a plurality of annular fingers 54 and 55 respectively extending fromring inside wall portions 48 and 49 respectively forming in each ringmember a plurality of spaced annular passageways 62 and 63 respectively.Within 360 annular grooves 19 and of ring members 51 and 52 respectivelyare disposed ring members 9 and 10 respectively having short fluid inletheaders 56 and 57 respectively, fluid header 56 having inlet 58, andfluid header 57 having inlet 60. Disposed 180 from the aforementionedinlets 58 and 60, are two outlets 59 and 61 communicating with fluidoutlet headers 165 and 166 in rings 9 and 10 respectively, so that fluidflows in two semicircular paths in passageways 62 and 63.

Between the aforementioned ring member 51 and the adjacent electrode 11there is disposed means for introducing gas, either a process gas or aquenching gas or some auxiliary gas, at a plurality of circumferentiallyspaced points around the electrode 11, the gas entering the chamber 50through the annular passageway 64. The annular passageway or opening 66constitutes a gas header, and in actual practice the arc heater wouldemploy two gas inlets to this gas header 66, one of these gas inletsbeing shown at 67, it being understood that another gas inlet spaced ifdesired at 180 therefrom would also be provided. From the gas header 66gas passes through a plurality of circumferentially spaced passageways68 and into annular space 69, thence through gaps or spaced Adjacent theaforementioned electrode 12 is a similar into the portion of the chamber50 Where the arc rotates. bores 70 into the aforementioned annular space64 and gas header 71 having gas inlet 72, gas from the gas header 71entering the arc chamber through the annular space 73.

It is noted that electrode 11 is separated from annular ring 51 byannular insulating means including annular insulating members 74 and 75,and that electrode 12 is electrically insulated from ring member 52 bymeans including annular insulating members 77 and 78.

It is noted that the remainder of the arc heater includes sectionalizedarc chamber walls, these including a heat shield generally designated80, which section may be eliminated if desired, a heat shield generallydesignated 81, and a heat shield generally designated 82. It is furthernoted that the right-hand end of the arc chamber 50 is closed by an endplug generally designated 84 and that on the left-hand of the arc heateras seen in the figure there is a nozzle generally designated 86.

It is seen that the aforementioned cylindrical heat shield 82 is fluidcooled by fluid flowing in passageways 88 and 89, passageway 88connecting with fluid header 91 and thence with fluid inlet 92,passageway 89 communicating with fluid header 94 and thence with fluidoutlet 95.

It is further to be noted that gas is admitted into the chamber 50 at aplurality of circumferentially spaced positions around the heat shield82, there being an annular insulating member 97 with spaced bores 98communicating with an annular passageway 99 which communicates by way ofspaced bores 101 with an annular gas header 100 which has a gas inlet,not shown for convenience of illustration, disposed at a convenientposition on the arc heater.

Gas is also admitted at a plurality of circumferentially spacedpositions around the end plug generally designated 84 and near the innerchamber wall of the heat shield 82. There is an annular space 102 whichserves as an auxiliary gas header, and an annular gasket of insulatingmaterial 103 having a plurality of bores 104 at spaced intervalstherearound to permit a quenching gas or an auxiliary gas or a processgas to be introduced into the chamber 50. The annular space 102communicates with annular gas header 106. It is further seen that theheat shield generally designated 82 is electrically insulated from theelectrode 12 by means 107, 108, and that the heat shield generallydesignated 82 is electrically insulated from the end plug 84 by means111 and 112 composed of insulating material. End plugs 84 is seen to befluid cooled, having a conical passageway 113 extending from fluidheader 114 connected to fluid inlet 115. The conical passageway 113communicates with a fluid header 116 connected to fluid outlet 117.

The aforementioned heat shield 81 is similar to the heat shield 82 andneed not be described in detail. Suffice it to say regarding the heatshield 81 that the surface thereof which faces the arc chamber 50 isfluid cooled by fluid passageways having fluid inlet and fluid outletheaders communicating with fluid inlets and fluid outlets. A gas isadmitted at a plurality of circumferentially spaced positions betweenheat shield 81 and heat shield and a gas is admitted at, or can beadmitted at, a plurality of circumferentially spaced positions betweenheat shield 81 and electrode 11, the last named gas passing through thepassageway 119 and through spaced bores 120 in an annular ring ofinsulating material 121. The gas header for the last named gas isdesignated 122 having inlet 124, while the gas header for gas admittedby way of annular space 155 the heat shields 80 and 81 is designated123, having a gas inlet, not shown, for convenience of illustration.

Particular attention is directed now to the heat shield 80, which iselectrically insulated from heat shield 81 by insulating means 125 and126 and electrically insulated from nozzle 86 by insulating means 128and 129. Heat shield 80 is cooled by fluid passing through annularpassages 131 communicating by way of holes 127 With a fluid header 132having fluid inlet 133, and communicating by holes with outlet header144 having fluid outlet 134, spaced from inlet 133 so that fluid flowsthrough two semicircular paths. Passageways 136 and 137 may be used forseeding or sampling or quenching or mixing purposes, but may be pluggedup by plugs 138 and 139, which may be secured thereto by bolts, notshown for convenience of illustration.

If desired, the heat shield 80 may be entirely eliminated from the archeater, and the arc chamber wall may comprise an up-stream heat shield82, and a downstream heat shield 81.

Gas may be injected between the aforementioned heat shield 80 and theaforementioned nozzle 86 by way of gas header 141 having inlet 142,header 141 communicating by spaced passageways 161 with annular space162.

The aforementioned nozzle 86 is seen to include a fluid cooled innersurface 146 having fluid flow passageway 147 near the inner surface, thepassageway 147 communicating with a fluid inlet header 148 and a fluidoutlet header 149, these communicating with inlets and outletsrespectively, not shown for convenience of illustration.

It is seen, then, that there is provided an arc heater with means forsupplying a large electrical current to the electrodes, symbolized byleads 151 and 152 connected to source of potential 153 to produce andsustain the arc 13; magnetic field coils 14 and 15 are energized to setup a magnetic field which causes the arc to rotate at a predeterminedspeed which is neither too fast nor too slow, the arc moving from anyparticular position before the intensely hot are spot has burned throughthe electrode, the are not returning to the same position until thatarea or that point on the electrode has had a chance to cool down to asafe temperature. It is further seen that gas may be admitted into thearc chamber at a plurality of points depending upon the process gas usedand the desired product. As will be readily understood, the process gasis pyrolized or decomposed by the heat of the arc and thereafter it iscooled to a temperature at which some desired recombination product ispresent in substantial proportion, the exact temperature of coolingdetermining in part the proportion of the desired recombination product.

It will be understood that the gap between electrodes 11 and 12 isadjustable, if desired by having a number of rings 51-52 of variouswidths available for use.

Particular reference is made now to Tables I, H, III, and IV which showthe results of tests runs. In all of Particular reference is made now toGraph No. 1, where variations in some of the products are charted forvarious flow rates.

In the curves of FIG. 2, the quantities of H CH C, and C H expressed inmole percentage are shown varythese test runs, the arc was powered byalternating cur- 5 ing with variations in the reciprocal of the flowrate of rent, and the electrode gap was inch. CH supplied to the arcchamber, and the curves corre- To insure purity of process gas andaccurate measspond generally to the values of Tables I and II. urementsof the recombination products, the arc chamber Particular reference ismade now to Table No. III, was flushed before process gas was admittedby supwhere the process gas employed was C H and the complyingchemically pure nitrogen to the chamber for several position of theproduct is analyzed with respect to the seconds. At the conclusion ofthe supplying of process gas three different flow rates and threediflFerent input powto the arc heater, nitrogen was again supplied tothe arc ers to the arc heater. heater for several seconds. Particularreference is made now to Table No. IV, The tables show results forvarious flow rates of the where product values obtained during the sametest runs,

process gas and various powers to the electric arc.

that is runs 4, 5 and 6, are shown with percent reference TABLEI.COMPOSITION INVOLUME PERCENT OF PRODUCT GAS IN CH; FLAME Composition,percent CH4, Power to Kw. hr./ Run No lbs./sec. gas, kw. Hz 00 CH4 CgHzCzHz 04111 Other lb. CzHg Percent reference to total carbon Run No CzHzC2H4 04H: 00 O her a process gas may be introduced at one or more of anum- 234 269 ber of points up-stream and down-stream of an arc to 5.2%38 2.3} assist in providing maximum production of the desired productfor a given kilowatt hours of power to the arc.

Tables I and H show a chemical analysis of the gas in the arc heaterwhere methane is used as the process gas, and the desired recombinationproduct is acetylene C H Further, although an auxiliary quenching gaswas not employed in the test runs described, out apparatus provides thata quenching gas or an auxiliary gas may be introduced at a number ofpoints up-stream and down-stream In obtaining test samples of gas forchemical analysis, a 3 of an are or substantially in the area of the arcpath.

TABLE IIL-COMPOSITION IN VOLUME PERCENT OF PRODUCT GAS IN CsHe FLAMEComposition, percent probe consisting of a water cooled concentriccopper tube with a 4; inch bore was employed, the bore opening of theprobe being at the nozzle, preferably of the axis thereof. Runs 1, 2 and3 are the same runs in Tables I and II with their results analyzed indifferent manners and show the results for different flow rates of thematane, and different input powers to the arc heater, together with thequantity of the desired output (Table I), measured in kilowatt hours perpound of the desired recombination product gas. Test run number 3 showsthat TABLE IV.CONVERSION OF CaHe TO PRODUCTS Percent reference to totalcarbon for a certain flow rate and are input power, the yield Run NoSoot can on. 02H; can, C3H4 0.11. of acetylene, measured in kilowatthours per pound of Q27 Q31 0.27 41 acetylene, compares very favorablywith presently used 13.83 5.48 1.56 0. 33

processes. In test run No. 3 which produced such efficiency in theconversion of Methane to acetylene, Methane was introduced at thefollowing points in the arc heater:

40% by gas inlet 67. 40% by gas inlet 72. 4% by gas inlet 124 and gasheader 122. 4% by the corresponding gas inlet (not shown).

for gas header 100. 4% by the gas inlet (not shown) for gas header 106.4% by gas header 123 and gas inlet 110. 4% by gas inlet 142 and gasheader 141.

Particular references made now to Table II, where test runs 1, 2 and 3are analyzed with respect to, or with reference to, the total carbon,and it is seen that the electrical and flow rate conditions whichproduce the most efiicient conversion to acetylene are also accompaniedby the production of the least carbon in the arc heater.

This invention constitutes a further development and advance in thechemical processing art, as described in the copending application ofMessrs. Bruning, Kienast, Kemeny and Hirayama for Cross-Flow Arc HeaterApparatus and Process for the Synthetic of Carbon, Acetylene and OtherGases, filed Nov. 12, 1965, Ser. No. 507,- 345; to that of C. Hirayamaet al. for Method and Equipment for the Pyrolysis and Synthesis ofHydrocarbons and Other Gases and Arc Heater Apparatus for Use Therein,Ser. No. No. 446,012, filed Apr. 6, 1965, now issued Pat. 3,389,189;that of P. F. Kienast et al. for Arc Heater Apparatus for ChemicalProcessing, Ser. No. 471,914, filed July 14, 1965, now Pat. No.3,345,191; and that of D. A. Maniero et al. for Process for HydrogenCyanide and Acetylene Production in an Arc Heater Having a Rotating Arc,Ser. No. 657,867, filed Aug. 2, 1967, now Pat. No. 3,460,902, all of theabove-identified patents and the above-identified application beingassigned to the assignee of the instant invention.

Whereas we have shown and described our invention with respect to anembodiment thereof which gives satisfactory results, it is intended thatall matter contained in the foregoing description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense; changes may be made and equivalents substituted withoutdeparting from the spirit and scope of the invention.

We claim as our invention:

1. Arc heater apparatus for chemical processing comprising generallycylindrical means forming an arc chamber, first and second axiallyspaced annular electrodes disposed in the arc chamber with an annulargap therebetween, the second electrode being the downstream electrode,means for producing and sustaining an are between the first and secondelectrodes, the arc extending generlly in an axial direction, means forcausing the arc to move substantially continuously around and betweenthe first and second electrodes and to describe a generally annularpath, means for introducing a process gas into the arc chamber through asubstantially circumferential path radially external to the electrodesfrom which the process gas passes in a generally radial directionthrough the gap between electrodes and through the annular pathdescribed by are movement, said are pyrolizing the process gas, andmeans located downstream of the second electrode a distancesubstantially equal to the distance between the arcing surfaces of thefirst and second electrodes for introducing a quenching gas into thechamber, the quenching gas acting to cool the pyrolized gas, and nozzleexhaust means for the arc chamber.

2. An arc heater for chemical processing comprising generallycylindrical means forming an arc chamber, first and second axiallyspaced annular electrodes disposed in the arc chamber with an annulargap therebetween and assisting in defining the arc chamber, the secondelectrode being the downstream electrode, means for producing andsustaining an are between the first and second electrodes, the areextending generally in an axial direction, means for causing the arc tomove substantially continuously around and between the first and secondelectrodes and to describe a generally annular path, means forintroducing a process gas into the are chamber peripherally spacedpositions between the first and second through a substantiallycircumferential path radially external to the electrodes from which therocess gas passes in a generally radial direction through the gapbetween electrodes and through the annular path described by aremovement and is pyrolized by the arc, nozzle exhaust means for the arcchamber, and heat shield means extending between the second electrodeand the nozzle exhaust means, the heat shield means being at leastseveral times greater in length than the distance between the first andsecond electrodes whereby sufiicient time is provided for the processgas after being pyrolized to be substantially cooled as it moves awayfrom the arc zone before being exhausted from the nozzle means.

3. Are heater apparatus according to claim 2 additionally characterizedas including means for injecting a quenching fluid into the pyrolizedprocess gas at some position along the length of the heat shield meansand before the process gas is exhausted through the nozzle exhaustmeans.

4. Arc heater apparatus according to claim 3 in which the heat shieldmeans is composed of tWo elongated sections and the quenching fluid maybe injected at a plurality of peripherally spaced points between the twosections of the heat shield means.

5. Are heater apparatus according to claim 1 in which the means formingan arc chamber includes a closing plug for the upstream end of the archeater and an elongated heat shield interposed between the firstelectrode and the closing plug, the space enclosed by the last-namedelongated heat shield increasing the volumetric capacity of the arcchamber thereby increasing the conversion effiency of the arc heaterwhere methane is the process gas and the desired recombination productis acetylene.

References Cited UNITED STATES PATENTS 3,343,019 9/1967 Wolf et al.313-32 3,182,176 5/1965 Bunt et a1 2l9-121 3,389,189 6/1968 Hirayama eta1. 23277 XR J. H. TAYMAN JR., Primary Examiner US. Cl. X.R.

23l, 209.3, 259.5; 20431l, 323; 219-75, 121, 123; 260-679g 31332, 231

